Weird. I am a bit puzzled as to why the purge tower is disabled manually though.
With filament change enabled, the nozzle wiping should occur somewhere. There’s a rather interesting thread on Purge-to object in Bambu Studio, but if you are not going down that route, it does make sense that the slicer wants to create at least a nozzle wipe skirt. That would be an intentional feature rather than a bug.
Try slicing with a purge tower or print object-by-object.